Logging site slash removal may be boon for wild bees in managed forests

New research suggests the removal of timber harvest residue during harvesting may be a boon for wild bees, an important step toward better understanding the planet’s top group of pollinators.

The findings are important because bees are the driving force behind $100 billion in global economic impact each year, with insect pollinators enhancing the reproduction of 90 percent of the Earth’s flowering plants, including many food crops.

Insect pollinators are also ecologically critical as promoters of biodiversity. Bees are the standard bearer because they’re usually present in the greatest numbers and because they’re the only pollinator group that feeds exclusively on nectar and pollen their entire life.

Researchers at Oregon State University spent two years studying 28 contiguous 1-acre clearcut sites. They assessed whether the abundance and diversity of wild bees was affected by the removal of timber harvest residue, also known as slash, and the soil compaction that goes along with it.

“Bees are important for biodiversity in managed forest landscapes but we just don’t have a very good handle on them in these areas,” said lead scientist Jim Rivers of the OSU College of Forestry.

The study plots occurred within a managed conifer forest in western Oregon. Each plot received one of five unique treatments, ranging from removing only the boles – tree trunks that are used to make lumber – without compacting the soil at all (no heavy equipment used on the plot) to removing all of the logging slash and compacting the entire plot.

The findings were surprising, Rivers said.

“The combination of the most intense timber residue removal and soil compaction treatment made for the greatest number and diversity of bees,” he said.